Easy Hard Sad Happy

Albert, Angus, Jacob, Jerry and Marcus have been hard at pre-IOI training in Sydney since last Thursday.

Today’s the last full day of prep before flying out to Japan tomorrow.

These pre-competition days are intense. They start with breakfast at 7:30am (Good Fat and a milkshake is a popular brekkie combo with the team) then a five-hour exam.

Here’s the team getting stuck into it this morning under the watchful eye of Team Leader Robert and Deputy Team Leader Ishraq.:

Here’s an example of one of yesterday’s problems called “Genetics” – this one came from the 2018 Baltic Olympiad in Informatics:

For villains that intend to take over the world, a common way to avoid getting caught is to clone themselves. You have managed to catch an evil villain and her N − 1 clones, and you are now trying to figure out which one of them is the real villain.

To your aid you have each person’s DNA sequence, consisting of M characters, each being either A, C, G or T. You also know that the clones are not perfectly made; rather, their sequences differ in exactly K places compared to the real villain’s.

Can you identify the real villain?

After the exam and some lunch (and discussion of some ridiculous selling of wheat futures), it’s a problem session until dinner.

To start the problem session, the team uses its tried and tested technique – Easy – Hard, Sad – Happy. As in, how did the team rate the problems? This helps the team decide on how best to work through the problems from the morning’s exams. You’ll see the team thought the problem called “Broken” was a Goldilocks problem – not too sad, not too happy, just right.

Robert has noticed that this year’s team seems to have a knack for solving the really hard questions thinking they were easy, and then looking at the easy questions as if they were hard. That’s what the whole pre-IOI training’s about – giving the team a chance to work on technique, see a range of different problems and get into the problem-solving headspace. Hopefully this year’s IOI will be really hard!

Tomorrow’s the last day for the team – a shorter exam in the morning, some laundry and last-minute supply runs, then off to the airport.